Genetic manipulation to display the desired trait in biological components has opened up many new avenues. Viral vectors have been identified as successful gene delivery vehicle. Since they have the limitations like acute toxicity, cellular immune response, oncogenicity due to insertional mutagenesis, limited cargo capacity, resistance to repeated infection and production and quality control alternatives, non viral vectors like lipids, polymeric compounds, carbohydrate dendrimers and polypeptide based systems have been demonstrated to be better alternatives. Nanoparticles, especially carbon nanostructures are being studied for gene delivery applications. However, most of the studies are restricted to the animal system or the cell lines. On the other hand non viral vectors for plant systems are relatively underdeveloped, except for a novel method developed by Sanford et al as recited in Nature, 1987 327, 70-73, using a particle gun that employs accelerated DNA coated micro gold projectiles, that deliver DNA into intact plant cells. As an improvement to the micro gold structure, Wang and co-workers synthesized mesoporous silica loaded with nano gold for multiplex gene delivery as published in Nature Nanotech., 2007, 2, 295-300. While the low density mesoporous silica covered with gold was shown to penetrate soft maize embryo, there was no demonstrable data to show penetration of hard embryo like the one of woody tree species.
Recently, a tetrapod sharp structure was reported to deliver DNA into the human cell line mimicking viral vector capsid where the tetrapod's sharp tip carrying the plasmid enters into the cell bringing out necessary transfection; in an article titled “Three dimensional functionalized tetrapodlike ZnO nanostructures for plasmid DNA delivery” by Leng Nie et al in the journal, “Small” 2006, 2, 621-625. Similarly, it is also reported that silicon nano needles (of 200-300 nm diameter) required a force of 0.7-2.0 nN) as compared to a carbon nanotube (of 30-40 nm diameter) that required a lower force (0.1-0.2 nN) to penetrate the plasma membrane by Vakarelski et al in Langmuir, 2007, 23, 10893-10896, that once again highlighted the utility of sharp objects for gene delivery type applications.
It is noteworthy to mention here that ample literature is available on the synthesis of metal nanoparticles by microbes, both intracellularly and extracellularly (reference is drawn to Narayanan, K. B. and Sakthivel, N. 2010. Advances in Colloids and Interface Science. 156 [1-2]: 1-13). However, no report on gene delivery through nanoparticles loaded on sharp edged supports is available, which can not only facilitate DNA transfer to soft tissues but also hard tissues.
Thus, the prior art survey reveals a need for a carrier of genetic material with sharp edges. Further, the carrier should also have adequate capacity to carry the genetic material and the sharpness to penetrate to hard material, but with less damage. The process of preparation of said carriers should be a simple, easy to implement and still fill the gaps in prior arts and needs in the art.